Disposable absorbent articles are useful for absorbing many types of fluids, including fluids secreted or eliminated by the human body. Superabsorbent materials are frequently used in disposable absorbent articles to help improve the absorbent properties of such articles. Superabsorbent materials are generally polymer based and are available in many forms, such as powders, granules, microparticles, films and fibers. Upon contact with fluids, superabsorbent materials swell by absorbing fluid into their structure. The superabsorbent materials quickly absorb fluids insulted into the articles and retain such fluids to prevent leakage and provide a dry feel even after fluid insult.
In general, superabsorbent materials are water-insoluble, and although they can absorb many times their weight in fluids, they are relatively resistant to biodegradation. As a result, a separate class of superabsorbent materials has been developed which focuses on biodegradation, known in the art as biodegradable superabsorbents, or “bioSAP's.” Unlike conventional polyacrylate superabsorbents, bioSAP's become biodegradable over time under conditions that promote microbial growth.
Certain biodegradable superabsorbent materials, such as those composed of crosslinked polysaccharides, tend to exhibit lower absorbency properties, particularly absorbency under load and gel bed permeability, versus conventional non-biodegradable polyacrylate superabsorbents. Thus, it is desirable in the art to improve the absorbency properties of such biodegradable superabsorbent absorbent materials. However, increasing one of these properties typically leads to a reduction in the other property. For example, attempts to increase absorbency capacity in such bioSAP's can result in sloppy gels with significantly reduced permeability. Similarly, attempts to improve permeability can result in a significant reduction in absorbency under load. Therefore, there is a need for biodegradable superabsorbents having high gel bed permeability and absorbency under load.